Need some help with cylinders

I seem to be having trouble posting here...hope this isn't a duplicate post.

I'm new to Solidworks and CAD in general and am having trouble with cylinders. I am trying to draw a cylindrical shape (like a piece of solid round bar). What I want to do is draw a cylinder and cut holes on various sides, some all the way through the cylinder, some from the inside to the surface, and some from the surface inwards a specified amount.

I started by sketching a circle, then extrude to length. It usually ends up where there are two planes through the center of the cylinder. Then, I sketched the holes I want to cut on one of these planes. I can make a cut from the inside out, but can't figure out how to make a cut from the outside in, without going all the way through to the plane.

I have discovered that I can create a new plane and this allows me to draw and cut holes at various angles, i.e. not only along the two intersecting planes. However, I still can't figure out how to make cuts from the outside surface inwards.

I also can't figure out if you can create a plane tangent to the outside surface of the cylinder. So far, I've only been able to create the plane referenced to an already existing plane.

I hope this makes sense and that someone can assist.

Thanks in advance!

Have you tried the hole wizard yet? This is a very useful tool if you have it.

I agree, hole wizard is very useful.
However you can also do something else, which can do things not possible with the hole wizard, such as lofts.
Make an offset parallel plane to one of the ones that you already have. To do this, click new plane, click on a plane that you want to offset, and click on distance. Make the distance slightly longer than the radius of the cylinder to make sure you dont leave a piece of the solid behind when you make the extruded cut. The plane should be facing the curved wall of the cylinder, not the flat ends. Now you can make a sketch on that plane and extrude it towards the cylinder for the amount of distance needed. Making a draft on the extruded cut or making a loft cut with this plane may also be useful.