Winzer,
Most profs expect you to show up, work hard, and be careful in the lab. They understand that your abilities are limited by your coursework and experience to date. In one research position, the prof gave me a programming task that was a bit beyond me. When I couldn't do it, he did it himself and gave me some simpler tasks without getting mad about it. Eventually my programming skills grew and I was able to complete the more complex programming tasks he gave me.
In an experimental lab, there are lots of mundane tasks, often involving vacuum systems or electronics. The profs don't mind showing you how to do stuff, but pay careful attention so that you don't have to be shown twice. Be willing to read the manual for equipment and use outside resources so that you don't take too much of the prof's time asking for repeated explanations.
You don't have to be a whiz at everything in the lab, but find a few things where you can really contribute. The bottom line for prof's regarding undergraduates helping in research is that the students are a net gain for the lab. You must save the prof and grad students more time and effort than they expend showing you stuff. You must show up regularly (on time), work hard, and grow in your abilities.
Be sure and take your prof's advice. If he wants you to take an electronics course or a programming course, do it.
I found a lot of mercy, kindness, and patience for my lack of abilities. But I worked very hard and tried to be dependable. Consequently, my undergraduate research was very fruitful, I was included as a co-author on two papers, I had good recommendations, and graduate schools were beating down my door.
Michael Courtney