The Request is an job assignment to a professional. You may fill the creation request form in three simple steps. In the first step you provide details about the request, for example you choose its type e.g. buying, selling, renting, evaluation e.t.c. In the second step you provide information about the property, for example its location. In the third and final step you provide contact details and an optional generic description. After creating the Request, professionals get notified and the request starts accepting Offers. The Request stops accepting offers automatically if some criteria would be met, like number of days passed since its creation or the number of Offers gathered. The creator of Request can stop it manually. After the Request has expired, its creator will be able to see the Offers and then he/she can choose the professional to collaborate with. This is the point where the WorkGroup starts, for which you may find out more in the corresponding question "What is a WorkGroup ?".
Note that the Request appears only to logged in users and not public on the Internet.