Drum track with Step Sequencer

I play piano. I can read and write piano arrangements. All my songs so far have just been piano and voice. I was using Sonar X3  or Notation to create sheet music of my songs. Yesterday I wondered how hard it was to create other tracks. I decided to add a drum track. 
 
I watched a couple of videos and then I dug out a book called Fast Track Drums 1 that I had bought some time ago, thinking it would help me adding drums to my music. In one video I watched, he used the step sequencer to create a drum "pattern". I was going to mimic exactly what he did, but when I added session drummer to a track, I had actual drum names. But his drums were labeled D3, B3, DB3, etc. I didn't know how to correlate mine with his. That's when I dug on the book I had bought. I read part of the book and then I came to a page where they had four simple patterns that they said had appeared on many hit records. I decided to try one. I entered the pattern into the step sequencer and then extended it to the length of my song. It sounded pretty good for my first attempt. But then I thought...the ending should be different. I tried to add something new using the step sequencer, but I extended up changing the original pattern. I undid the changes. By chance, I opened the staff view and I saw where the different drums were placed on the staffs and I was able to add my ending that way. Then it occurred to me that maybe my cursor wasn't in the right measure, so I tried it again. I was able to create a new pattern with the step sequencer without changing the original one. But then I couldn't figure out how to re-select the original pattern if I wanted to change it. So how are you suppose to do what I am trying? Or won't it work? Or is there a better way?
 
I was also wondering about the step sequencer itself. I looked in the reference guide, but I couldn't find the answers to my questions. What do the numbers mean? At first I thought they were measures because that's what they sort of look like to me. But when I added my pattern, it was really busy. So then I thought the numbers must be beats...four per measure. There are eight squares per number. I assume that each square represents a 1/16 note. However, after I created my pattern, I saw in the staff view that eight notes had been added to the staff, so I guess the boxes didn't mean 1/16 notes.  So what do they mean? And what if you wanted the drum to sound for  a half note? How do you do that? Or don't drums sound for a length of time like a half note. In my book, they assigned the bass drum a half note in the one pattern, so that's what I was mimicing.
 
Thanks.

Thanks. That helps a lot. I never noticed those numbers at the top of the step sequencer. Any reason why you normally set the step to 4 for 4/4 time. I assume 2 would be eight notes and 1 would be quarter notes.
 
Thanks again.
 
Kevin

Thanks. I have sonar x3 standard and I just purchased the Professional version.
Brundlefly... I presume you are talking about a midi keyboard. I do have an older Yamaha that connected to the computer through a joystick port. My computer doesn't have one of those ports. I have been thinking about getting a newer keyboard with a usb connection.
 
Mettelus, I'm not sure what PRV is an abbreviation for. I'll look at the Midi Pattern tool.
 
Thanks again.