RYA Dinghy Level 1 Start Sailing is where most adult beginners first get their hands on a tiller. You learn how to sail in all directions in a small dinghy, with an instructor close by until you are confident enough to go afloat under supervision. Nobody expects you to know a jib from a jackstay on day one.
Most centres run the course over roughly two days or a series of shorter sessions totalling about sixteen hours on the water. You will rig a simple boat, launch and recover it, steer with the tiller, and feel how wind direction changes what the sails want to do. Capsizes happen in dinghy sailing; your instructor shows you how to handle them safely. You will get wet. That is normal.
By the end you should be able to get afloat under supervision in light winds. Level 1 is not a licence to sail alone yet, but it is the foundation for RYA Level 2 Basic Skills, where you start sailing without an instructor in the boat. Under-16s may prefer the Youth Sailing Scheme, but adults are welcome on the National Sailing Scheme from the start.