I want to provide items on workshop for my game, so that player can do the same, but have no clue on how to start and such with Titan engine, please help

steam workshop is not included at the moment in TE.
you could change source to directly include it (since it is now open and free)
or use the technique that i used before the source became open, which is creating your own steam layer, and by doing so, have access to the full STEAM API:
on the project properties, you can add
include header : C:\public\steam\steam_api.h | C:\CallbacksSteam.h
(the callbacksteam was for my personal header to have linked callbacks, as TE editor was not friendly to the callbacks syntax IIRC)
include libraries : C:\XXX\steam_api64.lib

and that's pretty much all you need to have access to the Steam API.
then its pretty easy, you just have to follow the doc to know what to add for your need.
then you can start the steam part by calling SteamAPI_Init();

from there it is a matter to reading the workshop API provided by steam, and link it to the proper TE objects

I recommend adding the codes here:
https://github.com/Esenthel/EsenthelEngi.../Steam.cpp

and then submitting a patch to the engine source github.