Welcome to the forums!
Building your own business online is a great way to supplement your income. Before you begin though it is best to figure out what you want to do as doing something you are passionate about will make it far easier to build your business. Some choose to create their own products or services, some want to go the MLM route, while others prefer to be an affiliate and sell others products. From your post looks like you are wanting to do the affiliate thing and that's a great way to start to make some money.
What you need to do is first choose what kind of products or services you want to sell as an affiliate. Once you have chosen what you want to sell you then need to create a marketing plan - how you are going to sell, what kind of marketing you are going to do and etc. There is a vast amount of information on this forum to help you get started with most of that. Matter fact the forum itself offers $10 per referral for those that signup for the secret forum - http://marketersdomination.net/threa...d-Forum-Member - this gives you a way to earn and learn at the same time.
Creating a marketing plan means you need to decide how you are going to market the product or service you have chosen. This could include creating a website, writing content to take over Google rankings, maybe creating videos for youtube, creating ads for third part websites to promote the product or service and etc.