The key is if you're confident in your abilities, you go post bids to people looking for help in the areas in which you excel. Your best selling point is your own site (and any others you might have built or helped build). To be credible, you need some examples to show any prospective clients. Look to your strong suits and then bid on projects that match what you can do.

Most projects will get many bids, so your sell through is going to be based on the product you can provide (again, your site and any others you may have helped build). Bidding low won't necessarily get you the job - you need to offer a good product (product being your services) for a fair price.

As far as an hourly rate, just ignore that or insert '0' if it requires a field. Set your price on the project rather than the time frame.