So you have basted your quilt and you need to quilt it. [If you missed that tutorial you can find it here]. The easiest way to machine quilt is to do straight line quilting and so this is a great place for beginners to start.
You'll need to make a decision as to the pattern of your lines. Will they be vertical? Horizontal? Diagonal? Cross hatch? etc. Will you use your seams as guides? One popular way of quilting is to stitch lines that echo the seam lines, say a quarter inch away from them each side. Another popular way is to 'stitch in the ditch' of your seam lines. I personally am not keen on this method, for two reasons. Firstly if your points aren't perfect then it is hard to get this looking good on the front and back! And secondly, you will hardly see it on the front, in my opinion a quilt will look quilted if you can actually see the quilt lines! If you aren't using the seam as a guide you may find it useful to draw your lines on the fabric to give you something to follow. If you do this make sure to either use tailors chalk or a pen designed for this purpose that will disappear.
[I have in the past used Frixion Pens for this purpose but I have had some issues with these recently and so do NOT recommend them for this purpose any more. I found that on some fabrics that didn't totally disappear, instead they left a white heat residue. I've also heard reports of the pen marks reappearing if the item gets very cold. So whilst I still use them for measuring fabric out as the marks are hidden with the cut marks or in the seams, I do not recommend them for use on the top/outside of a project.]
Whatever pattern you decide on, a walking foot will be essential for quilting! Without it your machine won't be happy with the thickness of the three layers. I like to describe the walking foot like a crocodile. It has a second set of feed dogs on the top, which grab the top layer of fabric much in the same way as the feed dogs on the machine grab the bottom layer and push it through. This stops the layers of fabrics and batting slipped away from one another and becoming distorted.
All walking feet will have measurement guides on them in the shape of groove etc, which normally indicate an eighth and a quarter inch measures from the needle. Some may come with a bar attachment that click in place and can act as a guide up to about 2 inches. This allows you to set the distance and have evenly spaced quilted lines. Some really fancy walking feet will have interchangeable soles that might have a 'stitch in the ditch' guide on it.
Before starting to quilt, always run a tension test using some scraps of the same fabrics and batting you are using for your project. You may like to experiment with the length of your stitch.
When starting to stitch your first line of quilting I normally start with a line that will go through the centre of the quilt. Roll up half of the quilt so that you can get the quilt through the machine. Start stitching just off the quilt top on the batting and stitch onto the quilt top. Remove the quilting pins as you come to them. If you have the ability on your machine, you may like to select the needle down option so that the needle will hold the quilt in place whilst you remove the pins. There is no need reverse stitch or lock your stitches at the beginning and end of each row of stitching. Work your way along the quilt unrolling it as you stitch each line. When you reach the edge you can do the other half of the quilt in the same way.