You can generate your query on the right by combining the relevant blocks. Note that every block has to be attached to the red "query:" block, otherwise it is ignored.
Text-blocks are different to Field-blocks! You have to use one of the more bright green blocks to specify a field of an event, and the dimmer block on top for ordinary text. There are currently two Field-blocks. One with a drop-down for known Fields, the other one with an simple textfield where you can specify whatever field you want.
Please note the clickable "Try..." link above this description.