I want to connect some pads to ground(copper area) as in this PCB. how can i do this with easyEDA.
You need to use the Copper Area tool.
Please see:
https://easyeda.com/Doc/Tutorial/PCB.htm#Copper-Area
and:
https://easyeda.com/andyfierman/First_project_copy-c58f939e1c964d62a181a79f375f492b
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Brand new interactions and interfaces.
Smooth support for design sizes of over 3W
devices or 10W pads.
More rigorous design constraints, more
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Easy to use and quick to get started.
The process supports design scales of 300
devices or 1000 pads.
Supports simple circuit simulation.
For students, teachers, creators.
Brand new interactions and interfaces. 
Easy to use and quick to get started. 
You need to use the Copper Area tool.
Please see:
https://easyeda.com/Doc/Tutorial/PCB.htm#Copper-Area
and:
https://easyeda.com/andyfierman/First_project_copy-c58f939e1c964d62a181a79f375f492b