Hey, welcome to the hobby. So the encode/decode thing trips a lot of new folks up. Encode means your radio is sending the CTCSS tone along with your voice when you transmit — that's what the repeater needs to hear before it'll open up and retransmit you. Decode means your radio will only break squelch when it hears a tone coming back on the receive side. For getting into a repeater you really only need encode turned on. Decode is mostly a personal preference thing, some people turn it on so they dont hear random carriers or other repeaters on the same frequency, but it wont affect whether the repeater hears you. Now the Baofeng — make sure you've got the offset set correctly too. Most 2m repeaters around 146.940 use a -600 kHz offset, meaning your radio transmits on 146.340. If your offset is wrong or not set at all you could be transmitting on the wrong frequency entirely and the repeater would never hear you. Double check that first honestly because that's the most common thing I see with new folks on the UV-5R. As for calling, most people just wait for the repeater to go quiet then key up and say something like your callsign and that you're monitoring or looking for a contact. No need to be formal about it, just be yourself.