Is not an easy job for starter. You need to sand to smooth, then apply fille, then apply primer, then paint. Some will resand again to smooth it and apply another round of paint. Is hard work but is possible

You need to check the for gap, after you paint your door gap will be smaller our even no gap, this make open or closing very hard. Gloss paint is very thick. That is why is better to sand off the old paint.

Lacquer is thinner.