Hello all! I started up playing Pokemon Red for the first time and I've been having trouble with it.

>inb4 genwunner hurr durr

Anyway, I'm stuck on the route getting to the rock tunnel after beating the third gym. After hours of trying to avoid jumping over this one ledge, I keep messing up by pressing down. How do I stop myself from doing that? I've only been playing for 3 days straight, so I'm kind of inexperienced at the game. Please help.