Really the civil war isn't something you need to worry about until you/one of your fellow Romans has a Popular Rating of approximately eight, or you/one of your allies have a senate popularity rating of approximately two. From a look at the status your current map, I feel that the civil war may be a fair distance away, so shouldn't be something you should be too concerned about yet.

Senate Popularity increases with fulfillment of senate missions and conquest of additional provinces up to a total of approximately thirty-five. Increases can also be gained by having family members with senate popularity increasing traits.

Senate Popularity decreases at its fastest when about thirty-five provinces are gained. Further conquest, even when following senate missions, is harmful to your popularity rating which will fall more and more rapidly as you gain more land. Further ways the rating can fall is when mission requests are not obeyed, and when family members have senate popularity reducing traits.

Popularity with the people isn't quite like senate popularity, and continues to climb the more provinces you successfully conquer - unlimited! It does fall though if you lose provinces though. It also can be lowered by family members with senate popularity reducing traits.

There are two ways that the civil war may be declared. You can either reach a low senate popularity rating and refuse their demands for suicide, or you can declare the war yourself when the people consider you worthy.

For the former to work, you typically, as stated above, need either two or fewer senate popularity shields.

When the senate decide they hate you enough (about three shields), they will first start making missions which come tied in with penalties. These penalties include investigations, which usually come along with large fines, and exposure of secrets, basically a nasty trait for your faction leader.

If your senate popularity drops any further, then the senate will demand that your faction leader commits suicide. Refusal will result in you becoming classed as a outlaw (the senate and, usually, the other Roman factions declare war upon you), while acceptance provides you a few more turns to up your rating before they ask you again.

Bear in mind that this can occur to the AI, and, if it does, you have a choice over who to support. You, and the other Roman factions, can also, if this does happen, declare war upon any other Roman faction personally thereafter.

For the latter to occur, you usually require eight or more people popularity points.

When the people consider you highly enough, you will receive a message, informing you of a chance to take power. This should allow you to declare war upon any other Roman faction by attacking one of their cities or armies. By doing this, the senate will outlaw you, and the other Roman factions typically declare war against you (although sometimes the AI does choose to side with your faction).

Bear in mind that this can also occur to the AI. If it does, you will asked who you wish to support. You, and the other Roman factions, will also gain the opportunity to attack any other Roman faction if you so wish.