Click the fork button.

Clone your fork and set up your environment for development. I reccommend iterm, but use whatever you'd like.

In terminal window 1

git clone git@github.com:YOUR_USERNAME/use-http.git
cd ./use-http
yarn
yarn link

In terminal window 2 (your react app to test use-http in)

create-react-app use-http-sandbox
cd ./use-http-sandbox
yarn
yarn link use-http

In terminal window 1 (inside your forked use-http directory)

npm link ../use-http-sandbox/node_modules/react
npm link ../use-http-sandbox/node_modules/react-dom
yarn build:watch

In terminal window 2 (your react app to test use-http in)

yarn start

Now just go into your use-http-sandbox/src/App.js and import use-http and now you can develop. When you make changes in use-http it should cause use-http-sandbox to refresh localhost:3000.

Once you're done making your changes be sure to make some tests and run all of them. What I do is open up 3 different panes in the same iTerm2 window by pressing ⌘ + D on mac 2 times. In the far left I do yarn build:watch, in the middle I do yarn test:browser:watch (where you'll probably be writing your tests) and in the 3rd window I do yarn test:server:watch. It looks like this.

Push your changes to your forked repo.

Once you push your changes, you will see a link in your terminal that looks like this.

remote: Create a pull request for 'master' on GitHub by visiting:
remote:      https://github.com/YOUR_USERNAME/use-http/pull/new/master

go to that url. From there you should be able to compare your forked master branch to ava/use-http:master.