How to baste a quilt
There are various types of batting which are preferable for different uses or for achieving different effects but I wouldn't worry too much. Your quilt will NOT be ruined because you chose the 'wrong' one. I like natural wadding over synthetic as it is more environmentally friendly.
There are several options for basting but the least messy is pin basting. Quilters use curved safety pins to attach the 3 layers of the quilt together so they don't shift around too much for the quilting stage.
Ideally you will need floor space slightly bigger than your quilt but if not you can do half your quilt at a time, rolling up the other half. Just follow the guide below.
Iron your backing fabric (you may need to piece it together if it is large) and lay it right side down on a clean floor. Your backing fabric should be about 4'' bigger than your your quilt top.
Smooth it out (but not too taut) and tape the edges at intervals to your floor. If you have carpet or a rug you can pin your backing to the floor but be VERY careful not to step on them and make sure you remove them ALL when you are done.
Place your batting (or wadding) on top and starting from the middle and working to the edges, smooth it out so there are no wrinkles or puckers. Your batting should be bigger than your quilt top but not your backing - it can be helpful to see the backing as you might want to align seams or patterns.
Next place your top fabric right side up on top of your batting and smooth out as above.
Lastly starting in the middle use the pins to secure all 3 layers together. Work outwards in all directions pinning about 4-5'' apart.
You can also do this on a table top using the rolled up method.
Congratulations, you have made your quilt 'sandwich' and you are now ready to quilt!