Ok... none of the previous answers contained the word "kerf" or the set of the teeth in the blade, or asked what kind of wood you were cutting... so here goes a shot in the dark... "ridges" can mean almost anything.. opposite of grooves, lots of things and where where the "ridges" at on the edge you cut? on the face you had up, right at the edge? on the bottom of the cut? how thick was the wood? Is it laminated (like plywood)? Was it wood you were cutting? If the ridges are running up and down on the edge you cut across the width of the edge, they are most likely tooth marks from a blade that is made for rough cutting. If it was Sappy wood like white pine can be sometimes, and the ridges were on the face of the wood right at the edge, it is just sappy residue being wiped off the blade on the face of the piece. if the ridges are on the bottom of the wood (the side you had down on the table when cutting) they may be splinters , if you were cutting cross-grain. Google the word kerf and set in a saw blade, then study up on the correct blade for certain cuts, a crosscut blade will have a wider kerf than a rip blade, A rough cut blade will have fewer teeth per inch than a finer, finish cut blade, what you learn about one saw blade will carry over to hand saws, circular saws, Jig saws, etc. Another point that has been overlooked is, you could have a damaged blade.. one or two teeth that are sticking out wider than the kerf ot the rest of the teeth.
Good luck! and ask lots of questions till you understand what your doing right and what your doing wrong , and in no time you will be able to make fine furniture.
On the second part... I'll tell you like my dad told me... Son when it comes to tools you usually get what you pay for. Good tools aren't cheap but cheap tools are good to learn on... you learn how to do good work with junk tools and when you get a really good tool you can appreciate it for what it does.
Hope this helps.