Hi everyone !

This is my first time using this platform to practice my eEnglish writing skills, I hope I can have fun [with] writing with you guys.

I'm not sure why because it doesn't really make sense, but we usually use the plural of "skill."

"have fun with (something)" is definitely a correct wording, but since you use the word "with" again so soon after, it sounds a little better to remove the first "with," which is optional, to avoid repetitiveness.

Hi everyone !

This is my first time using this platform to practice my eEnglish writing skill,s. I hope I can have fun with writing with you guys.