If you have a picture and you want to change it to pdf I can recommend one of these two methods.
How to convert a photo to Pdf
you can open your picture with chrome browser and print it as a pdf.
1- Right-click on your jpeg file.
2- In the general tab, you can see the format of your file.
3- Click on the security tab.
4- You can copy the address of your file in your computer.
5- Copy the address in chrome browser address bar.
6- Print your file.
7- Choose “Save as PDF” and click on save key.
8- save your file.
9- You can right-click on your new file and click on properties.
10- you can see, the format of your file has changed to pdf.
For converting multiple pictures to one pdf file you can follow these methods:
How to convert pictures to pdf with Microsoft word;
1- Open Microsoft Word document.
2- Click on insert tab and then click on Picture.
3- Select the pictures which you want to convert them to the pdf file.
4- Save your file as pdf.
5- You can open your file as pdf now.
How to Convert Pictures to Pdf with Adobe Acrobat;
1- Open your Adobe-Acrobat program.
2- Select on combine files into pdf.
3- Add your desired pictures.
4- Click on “combine Files” to combine all pictures into pdf.