i have no clue how to put my own custom sprites into doom 2

I've just gotten into using modding tools on doom and i want to do an overhaul on the monster sprites by replacing them with my redrawn versions but i cant find a single helpful tutorial and experiment with the softwares i have has gotten me nowhere.(i play the game through GZdoom btw, don't know if that's relevant)

also how do i shrink imported images

First of all, of you plan to do anything more complex than simply a new map, you need a lump editor. The most used one is SLADE3, that you can freely download from its official site. If you already possess this software, you can use it to modify or to create new sprites. (This just in the case that you where also searching for a useful tool)

The ZDoom wiki is an excellent source of tutorials, so if you have any doubts you can check it.

Regarding your question, you can't directly modify an IWAD (SLADE3 doesn't allow you to save the changes) so you have to create a custom PWAD that contains the new graphics to replace the older ones. To do this, the easiest way is to use the inheritance function of the DECORATE code language.

I'm not going to explain every step of the work, mostly because I'm not so experienced in sprite management. 

However,  the previous mentioned wiki has some very interesting pages.

These explains how a sprite works and the procedure to create a new one:

https://zdoom.org/wiki/Sprite

https://zdoom.org/wiki/Creating_new_sprite_graphics

This is the main page of the DECORATE section of the wiki. You can read it if you want to have an idea of what DECORATE is

https://zdoom.org/wiki/DECORATE

This one is a specific page that explains how inheritance work (with some useful examples):

https://zdoom.org/wiki/Using_inheritance

Here you have the DECORATE definitions of the Doom's actors, to have an idea of what are you going to modify using inheritance

https://zdoom.org/wiki/Classes:Doom

Sorry if this is not the most useful answer, but I can't help you so much here

thamks

can i shrink imported png's i made in slade?

I have no experience in this but try to open your doom.wad (or doom2.wad) with SLADE and export the original graphics you want to change and then alter them with Gimp for example, and then import them again with SLADE into a new custom wad. When you run your custom wad in GZDoom the game would use your sprites over the originals.

12 hours ago, xenostar said:

thamks

can i shrink imported png's i made in slade?

For GZDoom you can use the TEXTURES lump to scale sprites.