How do you express the oppersite symbol to ^ ie mg^2 but i want it so the 2 becomes at the bottom of the g

Most of us write exponents as 2^3 etc as you have indicated. For subscripts, as in a chemical formula, say magnesium nitride, we write Mg3N2. Although the 3 and 2 are not written as subscripts, we understand that they are subscripts. For math symbols and physicals formulas, such as Vo*at, the capital letter and small zero shows that. Some students use the underline to show subscripts as the Mg3N2 formula above, they will write Mg_3N_2. Still others will make a statement that the numbers are subscripts. My suggestion is to do the best you can at explaining your problem and let us go from there. We can always ask if we don't understand the post. I hope this helps.