Proposal: Arts and Crafts
I can see advertisements of other sites on the sites I frequent.
How can we create such an advertisement for our site?
- In which sites are we permitted to advertise?
- What are the steps to do the same?
These are usually "community ads" (e.g. on Android.SE), but for Area 51 proposals which reach 85% or so, the Stack Exchange team often (always?) promotes proposals separately from the community ads to help reach full commitment. (Note that the ad you saw was indeed not a "community ad", but created by the Stack Exchange team.)
Community Ads are only available on graduated sites (i.e. no "beta" status), so if you are a user on a graduated site, like Android.SE, you can create a similar ad and post it in the relevant meta post (and wait for it to be upvoted). These ads are usually intended to benefit the community somehow, so I guess you could try DIY.SE or maybe GraphicDesign.SE or any other site you think would like to see/promote the Arts & Crafts proposal.
The design itself is available via the "Share This" link/button on the proposal page.