since you provided no information, I will guess that you used CSV format. If true, the blank results indicate you need to sync the CSV columns to the Outlook expectations.

tried to create csv file but it is showing blank. then tried to export the file in outlook .csv file but it is not visible to export.

Just curious why you would ask here how to use outlook?

Microsoft offer what is best described as the most basic of import facilities for Outlook. They never had a competitor they were trying to win users from so never bothered to fix the appalling proprietary only Outlook formats or offer importing in any of the standard data formats. Hence CSV is you only really viable choice.

Unfortunately CSV is so basic (I first used CSV in the 1980s) that is really escapes the level of ability of many people to manage.s CSV requires you to actually get involved in how the data is formatted and where it is placed, it is deceptively simple, yet complex enough to baffle many. This many be partially be because CSV itself has many sub standard that are in no way regulated or described. You need to look at the data in the file you write to decide exactly what the information looks like. There is no point and click or drag and drop that will work reliably.

Open the CSV file you wrote by exporting from Thunderbird in a spreadsheet program (not Excel it mangles the data trying to import it and just makes it much harder tan it needs to be.) I suggest LibreOffice. Similar enough to Microsoft office that those that are unaware Office is not the standard will not be lost. Standards compliant enough that the data you write is not polluted with Microsoft proprietary rubbish. CSV is a Unicode text file why Microsoft Office has so much trouble with it I do not know. Unicode was the default text for Windows XP. It is not as if it is new to Microsoft but it is only in the latest release that office actually considers it something that does not need to be "imported" and mangled in the process.

With the data file open in the spreadsheet you should see the information in columns under a heading. The heading is what is used to import to Outlook. Sometimes you need to change those heading into those the program importing expects to see, so export from outlook and have a look at the data that produces in your spreadsheet. are the headings for like data the same. Edit the file you intent to import to make the heading match the ones in the export file. Rarely is the order of the headings important, but having the right data in the column under the heading is very important. I have lost count of the folk that have imported CV into Thunderbird and complained that it did not work, only to find they had things like the email address is the town column, so their data did import, but it was uselessly spread all over the place under the wrong descriptors.

One of the true traps for young players with CSV is extraneous commas in their data. Given the columns are delineated using commas (and even that is not 100% accurate), an address set out like FLat3, Building 64, Main Street, London SW1H 0EU,United Kingdom

That would to a human be a street address, a street, a locality, a postal code and a country. However because of the missing comma in the locality postal code to separate them and the added one after Flat3 the columns will probably not be showing the correct data and this requires manual intervention to fix before saving the CSV again to import it to your desired location. I have historically spend days importing client databases via CSV into other applications and it is not a great deal of fun, It can be exacting and frustrating as you massage the data to fit the fields offered for import.