how can ı upgrade my items

i just started the game and I can't upgrade my items is there a level limit or shoul ı do mission

 

Do the basic initial crafting missions out of Kingshill (look for NPCs with green exclamation marks). After you've made your first random magic (blue) item by combining any 4 junk improved (green) items, check the Achievements tab in your Journal.

Look for the Crafting achievements category, and specifically the Equipment sub-category. You'll see that the first achievement in that list asks you to do 10 random green-->blue crafts; that turns into an achievement to perform 20 random blue-->purple achievements, etc. (I may have the # of crafts required per step wrong, but the Journal will tell you how many you need to complete for each step).

Once you've fully completed all levels of that achievement, you'll be granted a recipe to use the workbench to transfer Enchantments from any item to any other item. That's when you can start "upgrading" your equipment.

Before then, just use whatever happens to drop for you, and don't get too attached to any item as you will eventually find something with better base stats (which, by the way, cannot be improved; only the enchantments can be swapped around) and/or special bonuses.

You might want to put off even beginning this process until you've reached experience level 100. Focus on grinding up your Wisdom level instead; allocating Wisdom points give you more damage, defense, resources, etc. Go for crit rate first; mix in a bit of health / health regen, a bit of damage. Ignore block; postpone spending points on elemental magic resistance for now.

If you're still very new, you'll have to grind a bit before you can start going for Wisdom, as that feature is only first enabled at experience level 30. Wisdom can drop from any mob, but doesn't drop frequently; you'll probably want to start farming Boss rooms, either Normal difficulty if the boss is near your level, or Painful if the boss is 5 or more levels below you. Painful boss room entrance requires a Key of Prowess which you get by defeating Sentinel mobs. Sentinel mobs spawn when you clear a dungeon on Painful or higher difficulty (the Great Desert map which is accessible at around experience level 50 contains a Sentinel which respawns every 3 minutes or so on even Normal difficulty, so you'll end up farming that map a lot in the future).