How to ride METRO

Hi folks. I live in Galveston County and will be taking METRO from the Bay Area Park & Ride up to M.D. Anderson on Holcombe. The quickest route I've found so far is to take the 247 bus to the downtown station and walk over to the 700 train down to possibly the Dryden/TMC stop. I've downloaded the main Metro ride app and the Metro Q Ticket app. What I don't know is just about anything else. I don't eve know how to buy tickets. At one point I saw ticket prices in the main app, but when I just mapped out a route, I couldn't find any prices. And the ticket app confuses me. It seems I can increment my normal person tickets by full dollars, but when I hit 'buy now', it tells me that I'm buying a single ride pass for $10. Can anyone give tips for navigating and buying fares from Metro?