How to make instrument with wav-samples?

I'm working with Logic Express, but maybe you Pro guys have a solution for me... I'd like to control wav-samples with my controller keyboard, for example with the Exsp24. In Express I'm not allowed to create a sample instrument in the Exsp24. So the only way to use the wav-file is to drag it to the arrange or audio-window. But then I can't make a melody of it and I only have the sound... I can't control it. I don't have the money to upgrade to Pro, but maybe there is an non-expensive plugin that is helpfull for me? Thanks in advance for your advice.