It's pretty damn complicated, so here is my complete guide on how to do this.
As you can see there are two wooden crates and one nitro crate. Just push the crates anywhere you want, just make sure you dont get yourself stuck. Somewhat further you can see a switch to detonate the nitro on a high ledge, look at it.
now that you've done all this walk to the left edge of the screen and keep walking. you can get under the rock now, die and finish the level. You're welcome ;)