as admin of my site i wish to add articles by other authors. However wordpress always identifies me [admin] as the defalut author. I have tried the co-author plugin still the admin is defalut author in the metadata.
You absolutely can! Make sure that you are running an up to date version of WordPress, then go to Users -> Add New in your admin panel and add any new users you want to use as authors.
Then, edit one of your posts. In the top right hand corner select the “Screen Options” button. This will pulldown a menu. Make sure that the “Author” checkbox is checked. Underneath your WYSIWYG Editor will appear a panel called “Author” where you can select the authors name.
Unfortunately, you will have to register these authors. If you want to put a custom authors name you will have to add a function to your functions.php file that looks like this: