Programing Composite

[mguartes Profile]

i´m a new user and i´m traing to composite and display a function to make a progran which could make vectorial integrations.
But i can´t composite and displaying the function
For example:

If a(x)=x^2 and c=t , r=a(c) = t^2.

I'm trying to do this:

Local c,r,a
ImputFunc a(x)
ImputFunc c(t)
Define r(x)=a(x) | x=c

But when i made a "Print r" this give me an error.

Thaks and sorry for my english.