How do u put the drive belt back on a focus - 2000 Ford Focus

in the link for Serpentine Belt

https://www.google.com/search?q=how+to+replace+serpentine+belt+2008+ford+focus

This link for timing Belt

https://www.google.com/search?q=how+to+replace+camshaft+belt+2008+ford+focus

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the main digram for all drive belt ( flat belt ) is . first look to all pully make drowing out side with small paper 3 or 4 or 5 or 6 .....pully the main drive pully is crank . the end of you belt round the pully must be more than 180?? angl. alternator angl. more than 180 .compressor or water pump anther pully try use same digram .guide pully and belt tensioner no need to put angl .

Disconnect battery ground cable
Remove the ground wire (black) from the alternator
Disconnect the positive wire (red wire held on by a retaining nut) from the back of the alternator
Now disconnect the wire harness from the alternator
Remove the drive belt
NOTE: Some models use a belt tensioner that applies tension to the drive belt.
The best tool to use for this job is the serpentine belt too.
If you can borrow one from a neighbour you can get one at PartSource. (Part# 648451)
On other models you will have to loosen the adjusting bolt on the alternator bracket.
If you're not sure about how to remove the drive belt, visit your local PartSource for free print outs of car specific instructions.
Take off the mounting bolts from the alternator bracket
Now remove the alternator from the engine compartment

Installing Your New Alternator
Put the alternator in the engine compartment
Install the mounting bolts that connect the alternator to the alternator bracket
Connect the alternator wiring harness
Now connect the positive wire to the alternator
NOTE: Your new alternator should come with a retaining nut.
Remember to remove the nut before you install the positive wire.
If it doesn't keep the old nut.
Connect the ground wire to the alternator
Now install the drive belt
This is a great time to replace your old worn out belt. When inspecting your old belt look for signs of cracking, oil soaked, hard glazed, splitting or fraying.
All these signs mean it's time you replaced your drive belt.
If your vehicle no longer has the belt routing diagram under the hood, visit your local PartSource for a free print out of the belt routing diagram.
Reconnect the ground battery cable .

The tensioner does not need to be reset. It has tension to apply to the belt to keep it on at all times. If its weak you can move the tensioner by hand a full 1/4 inch. If that is so replace it

self ajusting must have bad pully or bearing in something

You need to disconnect the negative cable on the battery, then remove the drive belt, now remove the alt. attaching bolts. Raise the vehicle and remove the shield under the drive belt. Remove the air intake tube. Disconnect the connections to the alt. Remove the engine roll restrictor. Get a helper to push the engine back and pull out the alternator.

You have an intermitt issue. Test battery voltage when light is on. More than likely alternator (also check the belt that drives it) or poor battery connection (must be clean and tight).

Removing the Alternator
Disconnect battery ground cable
Remove the ground wire (black) from the alternator
Disconnect the positive wire (red wire held on by a retaining nut) from the back of the alternator
Now disconnect the wire harness from the alternator
Remove the drive belt
NOTE: Some models use a belt tensioner that applies tension to the drive belt.
The best tool to use for this job is the serpentine belt too.
If you can borrow one from a neighbour you can get one at PartSource. (Part# 648451)
On other models you will have to loosen the adjusting bolt on the alternator bracket.
If you're not sure about how to remove the drive belt, visit your local PartSource for free print outs of vehicle specific instructions.
Take off the mounting bolts from the alternator bracket
Now remove the alternator from the engine compartment There. You've removed the alternator. How easy was that?
Installing Your New Alternator
Put the alternator in the engine compartment
Install the mounting bolts that connect the alternator to the alternator bracket
Connect the alternator wiring harness
Now connect the positive wire to the alternator
NOTE: Your new alternator should come with a retaining nut.
Remember to remove the nut before you install the positive wire.
If it doesn't keep the old nut.
Connect the ground wire to the alternator
Now install the drive belt
This is a great time to replace your old worn out belt. When inspecting your old belt look for signs of cracking, oil soaked, hard glazed, splitting or fraying.
All these signs mean it's time you replaced your drive belt.
If your vehicle no longer has the belt routing diagram under the hood, visit your local PartSource for a free print out of the belt routing diagram.
Reconnect the ground battery cable .

http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?partName=Engine+Mechanical&pageId=0900c152801ececd&partId=0900c152801ececd

follow the link to fix ur serptentine belt on your car

well, the belt does not just fall off. If the belt has come off it's because one of the pullys have failed.there is only 1 belt on that car, there should be a diagram under the hood that says "drive belt routing"
You need to release tension on the tensioner pully with a serpentine belt tool or a long 3/8" breaker bar. rout the belt according to the diagram, then re apply the tension