insert page attachment using rest api in kentico 13 from non kentico project

hello concern,

i want to add kentico page attachment using field guid in kentico 13 but i am using another project for it can you help me with rest api to insert page attachement. below code i used in same project but i have to do it with rest api

HttpFileCollection oHttpFileCollection = files; HttpPostedFile oHttpPostedFile = oHttpFileCollection[0]; string fileFileName = oHttpFileCollection[0].FileName; if (spage != null) {

 DocumentAttachment attachment = new DocumentAttachment();
 Guid attachmentGuid = Guid.NewGuid();
 // Adds the file as an attachment of the page  e9193c3a - f32a - 447c - 905e-ef8e8e603dfe
 // attachment = DocumentHelper.AddUnsortedAttachment(spage, attachmentGuid, oHttpPostedFile);
 Guid fieldGuid = Guid.Parse("e9193c3a-f32a-447c-905e-ef8e8e603dfe");
 attachment = DocumentHelper.AddGroupedAttachment(spage,attachmentGuid,fieldGuid,oHttpPostedFile);
 spage.Update();
 spage.MoveToPublishedStep();
 spage.ClearCache();
 spage.CreateNewVersion();
 spage.MoveToPublishedStep();

}