GETTING A SHEEP FARM UP AND RUNNING
Sheep can be purchased from the open market for 1000* each. How many you want to buy to start with is up to you. 1x sheep will breed so you can start with one and wait for the lambs to appear to increase your flock. A sheep will need to reach 3 years of age before it will produce lambs. You can see sheep by right clicking on them and your park will receive the cash amount shown in the sheep UI indicators. Sheep have a maximum value of around 500* so you will need to decide when to sell them to maximise profits. 
Above: To buy sheep head to the CROP MENU and at the end you will find sheep controls.
Controling Sheep
Sheep currently have a few control options, these are follow the player or graze. Clicking on the follow player will make the sheep follow the player, Graze mode allows them to wander freely and find food for themselves. You can also speed the sheep up with the other menu button. These buttons are On/Off so if you want to stop the sheep following the player remember to click the button again. For sheep information use the sheep icon found at the top right.
Creating Pastures
In the CROP MENU you will find a pasture tool at the start of the Menu, select it. Once selected right click on your land to start creating pastures for your sheep. Sheep eat grass and the pastures will produce a lot of grass consistantly for them to eat. If you dont have pastures sheep will head towards grass to eat. You can fence sheep in to pastures if you wish. Gates and some fence code improvements will be added as development continues, for now just jump over fences. 
Above: An experiment using trees to keep the sheep in the field. 
Above: Your more traditional fence approach to keeping your sheep and lambs safe.
Coming Soon
I will be experimenting with field hedges as development continues. In the image above you can see that I have used spruce trees to form a basic hedge to keep the sheep in, opposed to a fence. This worked fairly well but will need some additional code and new models for hedges before its included in the game. Some sheep will die due to natural causes and simply vanish off the map. Other livestock options will be made available as development continues.