The campfire must be placed at your Homestead. To do this, click on the blueprint in your Backpack and put it down in an open area at your home location. You will then be given the option to build the item.
NOTE: The blueprints were previously available to purchase through your Almanac or shop, but that option was removed on October 17,2013. You must complete certain quest to unlock the Blueprints to purchase.
The Campfire must be placed at your Homestead. To do this, click on the blueprint in your Backpack and put it down in an open area at your home location. You will then be given the option to build the item.
It is possible to craft while the Campfire is being built by clicking on the yellow "Craft" button at the bottom of the upgrade screen. Similarly, to collect items from a building being upgraded, just click the yellow "Collect" button on the bottom of the upgrade screen.
Once all the parts are collected for the upgrade and you select "build now" you will not be able to craft anything until the building is completed. A timer above the building will show how much time is left until it is finished.
To craft an item, click on the campfire and add the ingredients from your backpack. You can click on the recipe drop down menu to select any recipe you've already created - the ones you can make will show a green dot next to the name. Any recipes you've made before, but do not have enough ingredients to craft will show up with a gray dot next to the name.
The easiest method to craft a recipe is to find the recipe in your Almanac and click "Craft" under the image. This will automatically move all the items from your backpack to the campfire and begin crafting.
Once the item is crafting, you will have the option to add Time Potion or Success Potion to the campfire. If the item has a 100% success rate, there will be no option to add additional Success Potion.
When crafting is complete, a purple exclamation point "!" will appear above the campfire. Click on the campfire to pick up your items.