what lvl do i have to be to go out of town?

This version (PC), and Apple version: Lv1 (No restrictions)
Nintendo Entertainment System version: Lv3

Although the outside world can be a dangerous place - put a few levels on in the relative safety of town first. There is plenty to do in town and beneath to keep you busy for a few levels.

true you got the arena is it worth doing that?

Why not ? Extra XP is always nice.
But there are of course more beneficial and less dangerous places to get XP and loot.
If you want to get out of town in the NES version before you reach level 3 just find and use the hidden town portal. Gems can be gained by fighting sprites.

thanks the problem with the arena is i think survival rating is 50/50 cause sometimes you get tought monsters

I didn't bother with the arena much, I just explored Sorpigal and the cave below Sorpigal, and then headed out of town when I'd been everywhere. There's no harm in looking around outside, just be aware that some places are dangerous and you may die a few times. Outdoors you can get into larger battles too, but those also tend to give better loot.

its fun i never had this with other rpg's that you dont go outside easy because the unknown challange that awaits you :)

I've played MM1 up until my characters reached around level 10 I believe. It's very difficult sometimes to navigate the land, and when you have a low level party you must get used to resting a lot and reloading the game when you get defeated. Also don't forget that you have at least 2 spellcasters with some powerful and useful spells available!

i have 1 sorcerer and cleric healing is very handy

NOTHING is to be gained by fighting sprites! (except pain, sorrow, and curses)

true i hate sprites as well