Just as the Internet has been called a ‘vast sea of information’ it also represents unlimited possibilities to find out how to do whatever you are seeking. Making money online is entirely possible if you are willing to expend the time and effort to build and develop a business.
If you keep in mind the theory that nothing is ‘written in stone’ you can have a flexible plan that can easily be changed as you learn more and/or change your mind about what you want to do. Nothing legitimate should have any contracts beyond month-to-month so that you can always back out of anything at any time for whatever reason. If there is a contract or large ‘admin’ fee for joining, R-U-N away.
You can join many affiliate programs free and earn commissions when you are able to generate a sale. You can stick with this model for the duration as many people have and are making millions (over time). It is very easy to start this way as they provide a ready-made web page that you can use to advertise. If you have any money at all to invest you can usually make more money and find higher quality products and services than you can for free. However if all you can afford is free, then go that way for now.
There are other models that may appeal to you to start making money online. For example, using an auction site or classified ad bulletin board to start selling merchandise. You might start this with no inventory or product just by identifying all the things that you have in your garage or house that are in good condition that you are not using.
If you see online business more like a store, then you can become an independent distributor of products. There are any number of niches that may appeal to you, such as health and beauty products like vitamins, diets and/or lotions (treatments). If you like the ‘high-end’ you can be a distributor for electronics (phones, computers) or telecom companies (satellites, wireless, etc). It is usually free to sign up to become a distributor.
Note that there should be no reason for you ever to have to purchase an inventory or purchase anything every month. Any reputable company knows how to ‘drop-ship’ and you would just process the orders and the company would ship it right from their warehouse to your customer. If you find a company that requires this type of investment, R-U-N away.
A really fun business to have would be if you have any talent with arts and crafts. You can create beautiful gifts and sell them online. You could create a simple website or even a blog that includes a list of your inventory including pictures, your price list and an order form. The easiest and free way to process payments is to use PayPal to do your sales transactions. They will provide the payment button, the code, etc., all for free and you pay only a very small fee on each payment received. Do not get involved with ‘shopping carts’ and ‘payment gateways’ that will cost you a fortune even if you never use them. Paypal accepts all major credit cards.