I'm new to SF. I'm trying to import some basic info to do a demo to our sales team. I have some opportunties I would like to import. When I use the data loader, it  says "ID VALUE OF INCORRECT TYPE." I am trying to link these opportunties to the accts that I have uploaded. Any suggestions on how to do this? Thanks!

I'm new to SF. I'm trying to import some basic info to do a demo to our sales team. I have some opportunties I would like to import. When I use the data loader, it  says "ID VALUE OF INCORRECT TYPE." I am trying to link these opportunties to the accts that I have uploaded. Any suggestions on how to do this? Thanks!