To apply for a Saudi visa, you can follow these steps:

1. Visit the official Saudi e-visa website or the Saudi embassy website in your country.

2. Choose the type of visa you need (tourist visa, business visa, etc.).

3. Fill in the online application form with your personal details, passport information, and travel plans.

4. Upload any required documents, such as a copy of your passport and a recent passport-size photo.

5. Pay the visa fee online using a credit or debit card.

6. Wait for your visa application to be processed. This can take anywhere from a few days to a few weeks, depending on the visa type.

7. Once your visa is approved, you will receive an electronic visa (e-visa) via email that you can print out and present at the Saudi border.

As for who is eligible for an e-visa to Saudi Arabia, the country has recently introduced a simplified e-visa system for nationals of eligible countries. The eligibility criteria may vary depending on the type of visa you are applying for, but generally, tourists and business travelers from certain countries are eligible for an e-visa. It is recommended to check the official website for the most up-to-date information on eligibility requirements.