This is an explanation on how to import eclipse project.
Open Eclipse, select your workspace and import project
File -> import
General -> Existing Project into Workspace
Select root directory: Select project folder and press finish.
In order to run the application from Eclipse it's necessary to create a manual configuration
Open Debug or Run Dialog
Then, select Flex Application and New
Modify URL or path to launch since it shows the following image
Apply change and press Debug or Run