To use Google's SMTP server with your personal hosting and domain, you will need to configure the DNS settings of your domain by adding the necessary DNS records.

Specifically, you will need to add the following two DNS records to your domain's DNS settings:

MX (Mail Exchange) record: This record specifies the mail server that should receive email messages addressed to your domain. You will need to add an MX record that points to Google's mail servers. The MX record should have the following values:
Name/Host/Alias: Leave this field blank or enter '@' symbol to represent your root domain.
Priority: Enter the value '1'
Value/Points To/Target: Enter 'aspmx.l.google.com'
SPF (Sender Policy Framework) record: This record specifies the authorized mail servers that are allowed to send emails on behalf of your domain. You will need to add an SPF record that includes Google's mail servers. The SPF record should have the following values:
Name/Host/Alias: Leave this field blank or enter '@' symbol to represent your root domain.
Value: Enter the following text:
"v=spf1 include:_spf.google.com ~all"

Once you have added these DNS records to your domain's DNS settings, it may take some time for the changes to propagate across the internet. This process can take up to 24-48 hours, but usually happens much faster.