Learn Spanish (Latin America): Ella anda mirando las baratijas del puesto. - She is walking around looking at the stall's trinkets.

The structure andar + [gerund] implies that the action is happening while moving around, or that it's being done repeatedly without a very specific focus. While está mirando simply means "she is looking" (right now), anda mirando adds a wandering feel, translating closer to "she is going around looking" or "she is walking around looking."

I know puesto as the past participle of poner (to put). What does it mean here?

In this sentence, puesto is being used as a noun. It means a "stall," "stand," or "booth," like you would see in a street market or fair. (As a noun, it can also mean a job "position" in other business contexts!)

Is there a connection between baratijas and the word barato?

Exactly! Barato means "cheap." Adding the suffix -ija (which often points to something small or of little value) creates baratija, which means a "trinket," "knick-knack," or "cheap item."

Just to review, why is it del puesto instead of de el puesto?