There are several different types of restraining orders available under Oregon law. This page is only a partial summary, and not a comprehensive list. More detail, and the required forms, may be found on the court's website here. You should consult with an attorney immediately if you have been subjected to domestic violence or if you have recieved a restraining order.
You can ask the court for a restraining order under the Family Abuse Prevention Act (a "FAPA order") if, within the previous 180 days, you have been physically harmed, threatened with physical harm, or subjected to sexual contact by force or threats of force. The perpetrator can be any person in your family or any person with whom you've had a sexual relationship in the past two years, or any co-parent of your child. If you've been subjected to such violence by someone who doesn't fit that description, you may instead qualify for a different sort of order. In either case, you should also call the police to report the incident as soon as possible.
You can ask the court for a Stalking Protective Order against any person who has repeatedly (two or more times) had contact with you that made you fear for your safety, or the safety of a family member. That fear must be objectively reasonable, as determined by a judge.
This type of restraining order is available only to people who are age 65 and over, or those who have disabilities that substantially impair their daily tasks. It is, however, available for a much wider range of types of abuse, including not just physical violence, threats, and sexual abuse, but also financial exploitation and emotional abuse.
The procedures for these types of restraining orders are similar. To obtain such an order, you must submit a petition to the court, describing the conduct that justifies the restraining order. Your local courthouse has forms available for this purpose. A judge reviews the petition, and, if your description meets the requirements, signs the initial order. The judge will not ask you for any evidence beyond your bare word at that time.
You must then have that order served upon (delivered to) the person being restrained (the respondent). You cannot do this yourself, but any other adult who lives in the state can do it. The county sheriff's office often performs this task, for a nominal fee (usually about $35). Once the order is served upon the respondent, it is effective immediately, and that person is prohibited by law from contacting you.
Once the respondent is served with the order, they have the right to request a hearing. This is done by filing a form with the court, within 30 days of being served. The court must schedule a hearing within 14 days of the request, or 7 days if child custody is affected. At this hearing, the person asking for the order (the petitioner) must show that the allegations in the petition are true, and that they have a reasonable fear of abuse in the absence of the order. But they generally only must show this by a preponderance of the evidence - a greater than 50% chance. This is a lesser standard than the requirment of proof beyond a reasonable doubt, that is required in criminal cases (even if the criminal case were about the same allegations).
A restraining order petition is a lawsuit, and entitles both sides to legal discovery and the right to counsel. If you have been subjected to violence or served with a restraining order, you should consult with an attorney immediately.