You can access a repeater by just selecting a frequency, mode, offset, PL tone if necessary, and then just hitting the PTT key. But the radio becomes far more useful if you save that set of repeater parameters to a memory location, and do the same for all of the repeaters or simplex frequencies you expect to use.
Once you have done that, you then only need to select a memory channel to begin using a repeater or simplex frequency. You can also scan all or some of the memory channels continuously in order to be alerted when any repeater becomes active.
Each brand of radio has specific programming methods and key pad operation modes, so instructions for programming any given radio would not be useful here. For that, get out your radio ops manual and start punching keys. I don’t know an easier or more effective way. It takes a couple of weeks of trial and error and reading the manual to get proficient with that.
If you want to program more than a few of the radio’s memories, there are software and cable kits to do that efficiently with your PC. One source is RT Systems Inc (http://www.rtsystemsinc.com). Using this type of utility also allows you to save the programming as a computer file which can then be used for back up of the radio setup, or for “cloning” another radio so that it has the same memory channel programming.
When testing your radio to see if you can activate or “bring up” a repeater after programming it, be sure to identify with something like “W7AND testing”. If successful you will see the repeater still transmitting for a short period (the “tail”) after you release the PTT (Push To Talk) key. You can also see the signal strength on your radio’s S meter.
Anonymous “kerchunking” of a repeater is not only illegal, but also annoying to other listeners. Sometimes it is necessary to repeat the testing, but try to minimize it. If you need to continue, announce what you are doing with something like “W7AND testing antennas” or “W7AND trying to find a good location” etc. You may even get some help in providing feedback on your signal quality.