Being in tune with yourself is the first step in the AXEview process. You can't play with others happily if you aren't in tune. Now there are several very good inexpensive tuners available on the market. A chromatic tuner will allow you tune almost any instrument hands free. There are specific bass and guitar tuners, that you have to switch for each string, they tend to be less expensive.
Another option is using a pitch pipe, and again there are version for guitar and bass, you blow on the pitch pipe and match the sound on your guitar. And lastly I will mention a really old tuning aid called a tuning fork, usually an A. You rap the fork on any solid object and it produces a tone that you can match on your guitar.
If you read the instructions on whatever device you decide on, they will no doubt make your tuning experience fairly pain free. Your first step whenever you pickup your instrument should be to make sure you are in tune. Modern Bass guitars actually hold their tune very well, but with temperature and humidity changes, it's always best to just check it first.
If you're playing with other musicians, most likely someone else will have a tuner. If you have a piano in your house your can use that. Of course then you have to learn what notes are where on the keyboard, which is never a bad thing to learn either. If you really want to go on the cheap try EBay or Craigslist, there are always good deals on used ones. Just make sure it's working, or returnable if it isn't.
Have no fear, AXEview is here! Yep we put together a video to help you tune your bass. Also in a side benefit, you get to learn what notes your open strings are. FYI your strings go from the largest (Open E) to next smallest (Open A) to next smallest (Open D) to the smallest string on a 4 string bass (Open G). The phrase "Open" means you aren't using your left hand to fret/play any notes.
Your mission now is to match the sound to what we're playing. We will play 4 times nice long Open notes, your goal is to match it. If you don't get it just right the first time, just use the controls on the video and rewind. You will hear a beating sound between your notes and ours, the faster the beating sound the more you are off, the closer you get the slower the beating sound. It takes some getting used to at first, but use your ears, you'll get it. After we play the Open notes, then we use a harmonic at the 12th fret, which means you put your finger above the fret, don't push down. This is the doubled string or 8th note or octave in a scale and much easier to hear on the bass if your ears aren't used to it. Don't worry about the terninology, we will cover Octaves in a future video, the Octave is a very important tool in your playing vocabulary.