;) i'm a new to quilting. so i hope this does'nt sound dump. i never hear or have read anything about the the grain of the fabric . does it matter if its on the straight grain or not. please help,i'm lost.

You do want to cut your pieces on the grain. If you cut on the "cross grain," this is referred to as cutting on the bias.
When making bias cuts, the edges of your pieces can stretch and distort through handling/sewing and pressing. So it is best to avoid these cuts whenever possible.
You can't avoid bias cuts when cutting triangular or round shapes, just handle these pieces carefully :D:D:D

it is very important to cut your fabric on-grain...if you cut bias it will stretch out of shape and be a bugger to work with.

First of all, welcome to quilting! You will quickly find yourself addicted to this site, and the people on here are so very helpful.

Straight of grain vs. bias:

When you hold the fabric with the selvage on the top, like a square, straight of grain is in a north-south or east-west direction. Bias is a northeast-southwest or northwest-southeast direction. The bias will also have more stretch to it, which is great for some applications, but basic quilt squares (esp triangles as at least one side will always be on the bias) may stretch a tad when sewing.

My non-quilting mother always told me the more you pin, the more stable it remains, so don't be afraid to pin...

And good luck! Enjoy and allow yourself to make mistakes, that's how we learn. Make a practice piece for new techniques, save them and put them together for a quilt for yourself - what fun to look back at your early work!

Actually it's not crucial your pieces be straight with the grain. In clothing construction pieces are cut with the grain or on the bias so they hang right and don't twist. A quilt doesn't have to hang. Plus the quilting will keep a quilt stable.

The main thing you want to watch is to make sure the edges of your pieces don't stretch when you sew them together.

Straight grain is the length. Cross grain is across the width of the fabric and bias grain is the diagonal.

If you look at really old scrap quilts that were cut with templates and scissors the grain tends to be all wonky since they just cut it however it would fit.