You first need to enable the contacts sync. -≥ Go to Settings - Data Synchronization - Google and put a checkmark on Contacts.
On your phone, if you go to contacts, you see on the right side of the contact's name the word phone(this means the contact is a phone contact) You have three types of contacts - phone, google and sim contacts. All of your contacts need to be google contacts, if you want to sync them with google. You can probably manually convert every single phone contact to google contact, but that would take a lot of time.
So to speed up things, you need to do this:
You need to transfer all your contacts to your computer, Outlook or such. Then delete all your contacts from the phone. From outlook you need to export all contacts to the .csv or .vcard file. Then go to Gmail and import all your contacts from .csv file. Connect your tattoo to the internet and again go to settings - data synchronization - Google, press menu and choose Sync now. It will then transfer all your contacts from gmail to your phone. Then all your contacts will become google contacts and you will be able to sync them with Gmail.
In the future, when you create a new contact on your phone, be sure to select google as type of the contact to be able to sync it with gmail.
But be very careful with this, make a backup of all your contacts before you do this.