Having just read the Urban Companion class option from the WOTC website (
Urban Class Features -- A Web Enhancement for Cityscape for anyone who is looking), I think there are a few misunderstandings.
The most important is that the raven, when using this option, isn't treated as an animal companion - it is effectively a familiar.
You should follow the familiar rules as presented in the sorcerer section (as modified by class option). Use one-half of your ranger level to determine the abilities that the raven gains.
Your character would use a master level of 2 for anything else which is based on class level (such as the master level chart). You'd use 4 for anything which is based on character level (such as the HD of the familiar).
As I see it, your raven gets the following:
treated as having 4 HD
Uses your base attack bonus of +4 instead of the raven's +0
Uses your base save bonuses of +4/+4/+1 instead of the raven's +2/+2/0
Uses either your skill ranks or its (whichever is higher) for skills
+1 additional natural armor adjustment
an int of 6
improved evasion
3/4 of your hit point total (per the Urban Companion feature)
can speak with other birds (gained at 1st-level per the Urban Compaion rules)
Speaks one language for being a raven familiar
In addition, you get a +3 bonus on Appraise checks if the raven is within 1 mile of you, and Alertness as a bonus feat if the raven is within arm's reach. Finally you share an empathic link with the raven, and when you cast a spell on yourself, you can also have it affect your raven if it is within 5 feet.
A side effect of the raven being effectively a familiar is that it is much more intelligent than normal animals and you don't need to use Handle Animal to teach it tricks (which only works for creatures with an Int of 1 or 2). Your raven will (initially) have an Int of 6 (which puts it at the low-end of human intelligence). You don't need to teach it tricks - it is effectively smart enough to figure things out.
One other consideation is that familiars are treated as magical beasts, not animals, so some of your animal-type spells won't affect it.
Now that we've got some of the rules cleared up... advice.
Fill out a notecard or page for your raven to track its stats and abilities if you haven't already. This will save you a bunch of grief in trying to keep track of everything. Start with the stats for the raven from the monster manual (or the SRD). Walk through the familiar section and apply each adjustement. Then go back through the Urban Companion and adjust for the stuff there. If you're using the SRD, I like to copy the initial creature, then edit it in Word, adding additional abilities and modifiers to the sheet as I apply them.
In-game: at your current level, the raven is probably best used as a scout or messenger, checking things out from overhead. As it can speak one of your languages it can spy things from afar and make reports. Even untrained it has a pretty good Hide bonus due to its size (and if you have ranks in Hide it is really going to be good at it). You can also use it to investigate stuff that is elevated or which you can't reach for some reason.
At your current level, you want to keep the raven out of combat. It simply isn't effective (and durable) enough to do much currently. When you hit 6th level that changes as the raven can be used to deliver touch spells to the far end of the battlefield.
Some final observations: Animal companions and familiars aren't the easiest thing when you're learning the game for the first time. They require you to keep track of more stuff when everything can already seem overwhelming. Selecting variant options also makes things more complicated as well. I usually advise newer players to stick to the core classes.