I have the replacement screen, the screening spline and the spline hand tool. I've never done this before and would appreciate any helpful advice. Thanks.
Do opposite sides first.
Make sure the screen is straight before you start.
Don't trim anything until you're done.
Also, when you pry the screen material in with the tool, make sure to not "tighten" the screen too much as you go along or it will bow the edges of your screen frame, especially if it's made out of aluminum.
Press in with the tool snuggly as you go along, then once you get one edge done, go back and pry it in further if everything stayed straight and even (without puckers.)
The do the opposite side the same way. I do the longer edges first, then the shorter edges.
You'll note that when you remove the splining material that was first put in, it's all one continuous piece. I recommend not using one single continuous piece when replacing the screen.
Once you get all four sides done, take a razor and carefully cut off the excess screen material.
Then pat yourself on the back!