Have a TI30Xa, i am trying to input 100 micro squared. how do I do this?

Usually you do not use the prefix micro by itself, it must be followed by the name of a unit: 1 micrometer=10^-6 meter. This being said, you want to enter 100*10^-6 and raise it to power 2.
For this you can use the exponent rules.

1. 100*10^-6=(10^2)*(10^-6)=10^(2-6)=10^-4; product of powers =>algebraic sum pf exponents
   
2. (10^-4)^2=10^(-4*2) =10^(-8) ; power of power =>product of exponents.

With your calculator: You have a key near which is written [10 to x]; you access the function with [2nd][10 to x]

In what follows, I will enter (10^-6)* 100 and square it. I will use the change sign (-) or [+/-] key
(-6) [2nd][10 to x] [*] 100 [=] [x^2] [=]

The first = calculates 100*10^(-6), the second [=] calculates the square of the number obtained after the first [=].
There are other ways that use parentheses to avoid ambiguities, but I think this is the safest one for you. Be warned that the result will most likely be displayed in scientific format, 1.00 -08 where the -08 will be raised with respect to the main level line. If not, the result will be 0.00000001