Hello Dr Bijaya Kumar Padhi
Seems you have tried to run the code from the command window. Stata does not allow the line continuation from the command window using the three slashes ///
Either you have to run the code from a do file or remove the three slashes and run it from command window. For example, try this code
use http:
asdocx tab immigrant bone_arthritis bone_backspin bone_backother bone_neck bone_fibro bone_lupus, template(table1) table_layout(autofit) replace