u/Asianspacecowboy47

I never done this before but me and a friend made a ramp that leads down so I can bring in and out my lawn mower, it stays straight for a while but as you know due to weather it’s beginning to curve up so my question is how do I bring it down? I forgot to mention the top of the broad to the ground or the other board is 4 and a half, the board by itself is 3 and a half

I have attempted to nail it in but I don’t think I’m doing it right, the nail I use(sand looking one) is 3 and a half but I haven’t use the other one. So could anyone suggest an idea to me? Thanks