First of all, there might be legal restrictions depending on the country you're planning to run the ICO in.
Basically, you design your product first, which in your case means preparing - at the very minimum - a whitepaper in which you explain the use case of your system, how it benefits the people involved, what the raised funds will be used for, what your 5-year outlook looks like etc. The key to this is transparency and legitimacy, as you want to build trust in your product and don't want to be taken as a scam. Furthermore, a lot of marketing will be involved by running a website which explains your idea and a lot of social media involvement, getting people to discuss your ICO. Next, you'd have to provide an online tool on your site for the actual token sale or outsource it completely to a platform that provides ICO services.
If you provide me with further information, I'd be glad to analyze your situation in a call.