f(x)=xsquared+10 and g(x)= square root of x-1 and i have to figure out g(f(-3) i just don't know how to do it because i thought you could not have a negitive under a radical?

You can if it is a square!

f(-3)=x²+10=(-3)²+10=19
g(f(-3))=g(19)....
Can you take it from here?

Note: the expressions contain very few parentheses so it is not clear they have been correctly interpreted. So check the calculations carefully.