Using the codes mentioned here http://gis.stackexchange.com/questions/16464/how-to-list-feature-classes-in-multiple-geodatabases-in-a-folder i was able to list all the feature_classes in multiple geodatabases within a folder. Problem is i don't know how to save the print results to a csv file. I knew, in theory - i have to create a csv file -> open it -> Append the "Print_results" to that file. Since i don't have any experience in python i don't know how to execute it. 

Currently i'm trying with this code

    import arcpy

    dir = r'D:\Test\gdb'
    arcpy.env.workspace = dir

    gdbList = arcpy.ListWorkspaces('*','FileGDB')

    filename = r'D:\Test\FC_List.csv

    with open(filename, 'wb') as myfile:
        wr = csv.writer(myfile,quoting=csv.QUOTE_ALL)

    for gdb in gdbList:
        arcpy.env.workspace = gdb               
        datasetList = arcpy.ListDatasets('*','Feature')     
        fcList = arcpy.ListFeatureClasses()         
        for fc in fcList:
            print arcpy.env.workspace,fc
        for dataset in datasetList:            
            arcpy.env.workspace = dataset  
            fcList = arcpy.ListFeatureClasses()    
            for fc in fcList:
                print arcpy.env.workspace,fc
            arcpy.env.workspace = gdb
            for each_fs in fcList:
                wr.writerow(each_fs.split(","))
                print (each_fs)

I've refered to the code mentioned here https://www.snip2code.com/Snippet/163571/Write-a-list-of-personal-geodatabase-fea. Actually, this code is creating the Fc_list.csv file. But only as an empty csv file