Have a better image quality

Hi people,
I just started up my WordPress blog, Very new to this. I’m trying to figure out how to have a better quality pic, because as I enlarge the pic in the blog, it becomes blurry. And how do I know the exact height and width of the image so it could be in alignment with the text?
Please help!

Thank you,

Hello there,

I hope you are doing well today.

When you enlarge a picture it will stretch to meet that size and lose some quality to gain size so you need to replace the image with a larger one that can accommodate the larger size, so usually 1500x1000 px would suffice.

Best Regards,