What are the steps to painting the front door? Do you have to remove

You should remove the door, since laying it flat reduces drips and runs.

To paint a door, take the door off the hinges and remove all the hardware. Clean the surface, including filling any cracks and sanding any rough spots if the door is made of wood. Prime the entire door. You can use a roller on flat sections, but will probably need a brush to paint the corners and edges if the door has raised panels. Allow the primer to dry, and sand any drips. Then apply two coats of paint, giving each coat time to dry thoroughly and sanding in between coats.

If at all possible, yes, take it off as you will get a better finish in the long run. I use my garage, I pull the car out into the driveway. And hang old flat sheets from the open garage door to cut the dust during the drying process. But, I have a locking screen door and a pile of dogs and a bunch of cats and a canary and a dragon, and, of course, me. 😆 And sleep on the sofa for a night or two.

But not absolutely necessary. Wash the door with TSP, let dry. Tape off areas not to be painted. Use a good primer like Kilz or Zinsser. Let that dry. Then apply good UV resistent paint formulated for outdoor applications. Let that dry and you are done.

I like to take them down myself, less likely to get a nasty drip down the surface or paint sticking to threshold. I put them on saw horses or buckets work too.

If you are going to attempt to do in place, mask off the threshold under the door. Tape off the edges. I like to use a 3" or 6" foam roller, and then I brush it off with a soft paint brush to remove any texture. A light sand prior to painting should do unless there is a lot of cracking paint, then use a sander and prime. I like a final coat of marine epoxy for a good weather-free top coat; Start real early. light coats dry faster.

We just painted an aluminum screen door this summer. We used Rustoleum since it is made for metal and outside. Spray paint will get you a coverage that will not show brush marks. I covered the window glass and screens with newspaper using the blue painters tape. I agree with the sanding between coats and follow the direction on the can of whatever you use for dry times. Spray paint will allow you to have lighter coats. vs. thicker with a brush. Good luck, you can do it!