Launching my ea



I would like to know how to succesfully launch my ea.

A warnings pops up : "No contexts (symbols) found, aborting".

All I know is that thoose are forex symbols and i can look at the quotation mark if i click on display.

Also : when starting the robot, what does "allow the modification of signal parameters" mean.

and : what does "allow algorithmic trading" mean, since it's done by a robot.

Then : what is the "magic number" ?

Finally, please correct me if i'm wrong :

Fix lot will trade always the preset amount

Autolot will have amounts chosen by the robot

Lot is what the users fixes in fix mode

Deposit step is how the autolot will evolve.

Thank you