The easiest foundation repairs usually involve narrow cracks less than 1/4 inch wide . When the cracks are located in places where concrete tends to crack naturally the repairs are the easiest. Natural cracking occurs from shrinking. You can probably even ignore these cracks, but if water is seeping or they are unsightly you can apply epoxy putty or a high-quality silicon caulk which is paintable.
For larger cracks in concrete read the blog entry about larger cracks.