Current monitor

Hello!

I'm working into a project where I need to measure the current, actually I'm using a multimeter to do it,
but I want to use arduino to improve the measures, so, How can I do it? I have a very basics knowledges in electronics
I designed and develop a program that measure the voltage and storage into a data base, my program can display a graphics of this
but I really need to measure the current. In my laboratory we have some kind of bio-battery that produce energy so I need to measure the current.
somebody can help me?

PD
Sorry for my english

Thanks for any help!