I joined praise team and im playing electric but i can't improvise. can someone help me?

i recently joined my church's praise team. i was igned to play electric guitar. so far i've basically just played acoustic and I've just recently started playing electric ( well more like a couple months ago). the thing is, i can't improvise on electric guitar just based off of chords. the first 2 songs are "heart of worship" by Matt Redman and Blessed be your name by Matt Redman. We're supposed to have learned these two ( or in my case be ready) by next friday. please help me figure out something to play off of chords, because i know you can't just teach someone to improvise over the internet. any tips or any help at all would be appreciated! =]